Accessory drive



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ACCESSORY DRIVE Filed Sept. 23, 1944 Patente-d Aug. 17, 194s ACCESSORY DRIVE Vctor E. Matulaitis, Rochester, N. Y., and Frank- 'lin W. Edwards, Detroit, and Henry R. Voorhees, Grosse Pointe Farms, Mich., assignors to Chrysler Corporation, Highland Park, Mich., a corporation of Delaware Application September 23, 1944, Serial No. 555,480

4 Claims. (Cl. 172-284) This invention relates to means for driving motor vehicle accessories from the engine of the vehicle. More particularly it relates to an lmproved means and apparatus for driving a wind- 2 The slip ring I1 is connected to one end of the coil, the other end being grounded to the frame. The member I5 is provided with peripheral teeth 2l, the purpose of which will be explained.

shield wiper, but almost any other type of acces- 5 A flange 22 and a nut 23 retain the member I5 sory may be driven by similar means, either alone on the shaft l I for rotation therewith at generor in combination with the wiper drive. ator speed which is some multiple of engine speed Our improved driving means makes it possible as determined by the driving pulley diameters. to drive the Windshield Wiper mechanism directly The eddy-Current Coupling driven member 24 from the vehicle engine at a constant speed reis mounted on shaft II for rotation relatively gardless of engine speed. thereto by means of a stub shaft extension 25 It is the prime object of the invention to proformed integrally therewith. An anti-friction vide an improved means for driving the vehicle bushing 26 separates the shaft 25 and bore I4, the windshield wipers, shaft and bushing'being of sufficient length to Another object is to provide means for coupling insure a rigid SnDDOrt fOr the member 24. the wiper mechanism to the vehicle engine such The member 24 is 0f dished annular form and that the wipers are driven mechanically from the has a pair of copper rings 2i disposed within the engine, dished portion in radial alignment with the teeth A further object is to provide a constant speed 2| 0f the driving member. drivc for a Wiper mechanism driven from the When the coil I 6 is energized a magnetic field angina is set up around the coil, the iiux path of which A still further object is to provide a simple, includes both the members I 5 and 24. Regions cheap and rugged drive means for accomplishing 0f alternate high and 10W lllX density are Set 11D tho foregoing and one which has inherent shock in member 24 because of the teeth 2| which of absorbing characteristics. 25 course decrease the air gap where they are lo- ()tnor objects and advantages will be apparent cated. When member I5 is rotated, the member from tho following specification which describes 24 tends to rotate with it. This is due to the fact a preferred embodiment of the invention, that eddy currents are induced to ilow in mem- Thc accompanying drawing illustrates the dobers I5 and 24 because of the variation in ux vico in section, density caused by the teeth 2| passing by points Referring to tno drawing, it may be soon that of member 24. These eddy currents produce a we have shown in partial section a generator I0. flux which ODPOSGS the mein fluX and this coungenerator is the regular engine mounted ter"f.lux irl-accordance LenZS 131W, tends to generator conventionally found on motor vooppose relative rotation of the coupling members. hicles. For the sake of brevity we have omitted The member 24 Will iherefOI'e, tend i0 apthe engine, windshield and wiper blades, it being proach the member l5 in Speed and rOtate Syndeonicd snfnclcnt to stato that our invention is chronously therewith. Synchronous rotation is of applicable to practically any standard motor vocourse impossible because of inherent losses and niclo as will be readily understood by those the device operates with a slip between the drivskillcd in the art. 4o ing and driven members which varies in accord- The generator lo has the Conventional arma ance with the designed characteristics of the couture (not shown) mounted on a shaft Il having Pung and With the l0ada reduced portion I2.supported in the end bear- Fixed t0 the frame 01 body 0f the Vehicle is a ing I3. The shaft I I differs from a standard Support and gear housing 28 This hOU-Sing Congenerator shaft in that it is longer and the elontalus a Worm 29 disposed in mesh With a Worm gated portion has an internal bore |4. wheel 30. The latter is connected by means of a Mounted on the reduced portion I2 of the shaft exble drive Cable 3| With the Wiper mechanism is a driving member I5 of a magnetic clutch or 0r other accessory t0 lbe dllVeIlcoupling of the eddy-current type. This driving The Worm Shaft 32 mounts s plate 33 to which member I5 is of magnetic material and of 50 are attached Ahy Welding, brazilie 0r the like, a U-shape in section. A field coil I6 is carried by number 0f ileXible Connectors 34- These Conmember l5 and is adapted to be energized by nectors may be of Phosphor bronze, spring steel means of a slip ring I'I and brush I8, the latter or other material that will withstand continuous being carried by a brush holder I9 preferably flexing. Each of the connectors is fastenedlto a mounted on the generator housing as shown. hub 35 formed integrally on member '24 by means astma@ 3 of set screws 36. At least two of the connectors disposed opposite each other carrying weights 81.

The weights 31 are of such size that centrifugal force will act to move them radially outwardly and thus shift the member 24 bodily toward the right a predetermined distance at predetermined speeds of rotation.

Shifting of the coupling driven member 26 axially of the assembly will lengthen the air gapand lower the efficiency of the coupling with consequent drop in speed of the driven member.

vThe slip under normal conditions with the parts positioned as shown in full lines is in the order of 3%. As the speed ofthe driven member tends to increase above a desired maximum the weights 31 will move outwardly and shift the member 2d axially toward the right whereupon the slip will increase.

It will thus be seen that regardless of the variation in speed of the generator shaft ii caused by variation in the speed of the engine, the speed of the coupling driven member 24, and of the wiper blades or other accessory, will remain substantially constant, the Weights 3l hunting to provide speed regulation.

The present arrangement provides an exceptionally convenient and satisfactory drive for a vehicle windshield wiper. By mounting the eddyycurrent coupling on the generator wiring is simplied and accessibility is good. Our improved drive provides a mechanical driving connection between the wiper mechanism and the engine crankshaft which provides constant speed for the wipers and excellent shock absorption, the eddycurrent coupling slipping readily in response to momentary stoppage of the wiper blades due to ice, etc. The latter feature is important and eliminates breakage of the cable 3i which has been a source of trouble in existing designs.

It will be understood that we have illustrated but one of the many forms of our invention and we do not intend to limit the same in its broader aspects except as set forth in the appended claims.

Where our invention is employed to drive windshield wiper blades, reference is made to the copending application of Franklin W. Edwards Serial No. 546,405 filed July 24, 1944, which illustrates a suitable typical arrangement of blades which may be driven from our cable 3i as will be readily understood.

We claim:

1. An electromagnetic coupling comprising, an input member; a shaft mounting said input member and having a hollow bore; a dished output member surrounding said input member and having a stub shaft adapted to be received in said bore; an axially rigid driven shaft; radially flexible members connecting said output member and said driven shaft.

2. An electromagnetic coupling comprising, an

input member; a shaft mounting said input meming a stub shaft adapted to be received in said v bore; an axially rigid driven shaft; radially flexible members connecting said output member and said driven shaft, and weights carried on said members whereby said output member is shiftable by centrifugal force.

3. A coupling between `a driving shaft and a driven shaft comprising an input member secured to said driving shaft, means associated with said input member and adapted to create a magnetic field, an output member adapted to be positioned directly in said magnetic field and axially withdrawn from the immediate field, a second means providing the only operative connection between said output member and said driven shaft and adapted to transmit rotation from said output member to said driven shaft, said second means being speed responsive and adapted to withdraw -said output member from said immediate eld in response to increases in its speed of rotation whereby the speed of rotation of said output member is governed by said second means.

4. A coupling between a driving shaft and a driven shaft comprising an input member secured to said driving shaft, means associated with said input member and adapted to create a magnetic field, an output member adapted to be positioned directly in said magnetic field and axially Withdrawn from the immediate field, a plurality of weighted flexible elements providing the only operative connections between said output member and said driven shaft, said elements being adapted to transmit rotation from said output member to said driven shaft and being adapted to flex and withdraw said output member from said immediate magnetic eld in Iresponse to centrifugal force.

VICTOR E. MATULAIIIS. FRANKLIN W. EDWARDS. HENRY R. VOORHEES.

` REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,553,621 Locklin Sept. 15, 1925 1,787,648 Waters Jan. 6, 1931 1,887,284 Brady Nov. 8, 1932 2,025,487 Winther Dec. 24, 1935 2,193,214 Winther Mar. 12, 1940 2,243,016 Pritchard May 20, 1941 2,271,087 Maier Jan. 27, 1942 2,280,736 Winther Apr. 21, 1942 

